1. Field of the Invention
The present invention relates to a thermoelectric conversion apparatus for converting thermal energy into electric energy.
2. Description of the Related Art
Using a thermoelectric conversion apparatus for the conversion of waste heat discharged from an internal combustion engine, a fuel cell, etc., for example, into electric energy makes it possible to greatly increase the overall efficiency of a system including such a thermoelectric conversion apparatus.
For example, thermoelectric devices and the Rankine cycle are known for use in thermoelectric conversion processes for converting thermal energy into electric energy. However, the thermoelectric devices are disadvantageous in that their materials suffer a low performance level. The problem of the Rankine cycle is that an expander causes a large loss especially for small-scale electric power generation. Both the thermoelectric devices and the Rankine cycle fail to achieve a sufficient conversion efficiency.
Japanese Laid-Open Patent Publication No. 2005-33960 discloses a thermoelectric conversion fuel cell that operates according to an electrochemical process using a hydrogen storage alloy and a hydrogen concentration cell. The thermoelectric conversion fuel cell is advantageous in that the conversion efficiency is not liable to be affected by the scale of electric power generation and in that the mechanical loss is small.
The thermoelectric conversion fuel cell has an electrolytic membrane (proton-conducting membrane) made of a solid polymer. Thus, the electrolytic membrane needs to be humidified. However, the hydrogen storage alloy is unable to function sufficiently in the presence of water.